V1.3.3 hotfix

[jeromekelleher]

This cherry-picks commits involved in fixing dirac/beta coalescent issues onto the 1.3 series hotfix branch (which has had SMC K commits removed, see #2312).

The merge was slightly tricky as the C code is moving around quite a bit at the moment (hence the need for a hotfix in the first place) so it would be great if you could have a quick look to see if it seems ok to you @JereKoskela

[JereKoskela]

Looks fine to me.

[codecov]

Codecov Report

Attention: Patch coverage is 83.67347% with 8 lines in your changes missing coverage. Please review.

Project coverage is 91.46%. Comparing base (f6198b1) to head (dcc3d2c).

Files	Patch %	Lines
lib/msprime.c	82.97%	5 Missing and 3 partials ⚠️

Additional details and impacted files

@@                Coverage Diff                @@
##           v1.3.3-hotfix    #2313      +/-   ##
=================================================
- Coverage          91.51%   91.46%   -0.06%     
=================================================
  Files                 20       20              
  Lines              11329    11327       -2     
  Branches            2306     2304       -2     
=================================================
- Hits               10368    10360       -8     
- Misses               523      527       +4     
- Partials             438      440       +2     

Flag	Coverage Δ
C	91.46% <83.67%> (-0.06%)	⬇️
python	98.70% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.